Re: [PATCH RFC 2/5] s390x: implement diag260

[Heiko Carstens]

On Wed, Jul 15, 2020 at 07:51:27PM +0200, David Hildenbrand wrote:
> > Regarding documentation (some linked in the cover letter), so far I have
> > (generic/x86-64)
> > 
> > 1. https://virtio-mem.gitlab.io/
> > 2. virtio spec proposal [1]
> > 3. QEMU 910b25766b33 ("virtio-mem: Paravirtualized memory hot(un)plug")
> > 4. Linux 5f1f79bbc9 ("virtio-mem: Paravirtualized memory hotplug")
> > 5. Linux cover letter [2]
> > 6. KVM forum talk [3] [4]
> > 
> > As your questions go quite into technical detail, and I don't feel like
> > rewriting the doc here :) , I suggest looking at [2], 1, and 5.
> 
> Sorry, I suggest looking at [3] (not [2]) first. Includes pictures and a
> comparison to memory ballooning (and DIMM-based memory hotplug).

Ok, thanks for the pointers!

So I would go for what you suggested with option 2: provide a new
diagnose which tells the kernel where the memory device area is
(probably just start + size?), and leave all other interfaces alone.

This looks to me like the by far "cleanest" solution which does not
add semantics to existing interfaces, where it is questionable if this
wouldn't cause problems in the future.